Slide rule



Patented Oct. 10, 1922.

UNITE-D STATES PATENT OFFICE.

WILLIAM L MILLER, OF MADISON, WISCONSIN, ASSIGNOR TO GISHOLT MACHINE COMPANY, or MADISON, WISCONSIN, A CORPORATION 0F WISCONSIN.

SLIDE RULE.

Application mea May 5, 1920. serial No. 379,151.

To all whom t may concern.'

Be it known that I,- WILLIAM L. MILLER, a

citizen of the United States, residin at Madison, in the county of Dane and tate of Wisconsin, have invented certain new and useful Improvements in Slide Rules, of which the following is a specification.

This invention relates to improvements in slide rules of that vgeneral character which are employed for computing purposes; the several elements of the rule bearing scales indicating various data, and the information being obtained by setting the several elements of the rule to certain relatlve positions corresponding with known factors of the result to be ascertained.

One object of the present invention is to provide a simple, inexpensive, easily manipulated and reliable rule for computing the time required to effect the turning of a piece of work in a lathe, when the diameter and length of the piece are known, the cutting speed per minute, and the feed per spindle revolution.

Another object of the invention, which is independent of the particular data borne by the rule and of the particular matter to be computed, is to provide a slide rule having a body or. holder and a plurality of relatively movable slides, wherein the slides having been set to a predetermined position relative to each other, will possess suffcient fric-tion to be moved together in the body or holder without danger of relative displacement or disturbance during such movement.

Other objects and advantages of the invention will be apparent to those skilled in the art from the following detailed description, taken in connection with the 'accompanying drawing showing one practica-l embodiment of the invention, and in which- Fig. `l is a top plan view of my improved slide rule;

F ig. 2 is a ,cross-section' through the body or holder, as viewed from the right of Fig. 1

F ig. 3 is a similar cross-section of one of the slides which has a width substantially equal to the full internal width of the body or holder;

Fig. 4 is a similar cross-section of the narrow slide which is frictionally engaged with the wide slide shown in'Fig. 3; and,

grooves or channels 13 and 14, respectively,

in which is mounted a slide 15, shown in cross-section in Fig. 3. The upper marginal portion of the slide 15 is folded over as shown at 16, in order that the said slide may have a light friction fit .in the upper channel 13 of the body; and the said slide 15 is formed with a laterally oiiset base or flange 17 which .extends down into the lower groove 14 of the bod The lower of the two slides designated by 18 and shown in detail in ig. 4 is a Hat strip of metal, with its lower marginal portion folded back as shown at 19 so as to frictionally embrace the lower portion of the offset baseI or flange portion 17 of the wider slide 15. lower folded portion of the slide 18 engages in the lower channel 14 under light friction, while the friction of the slide 18 and the grip of its folded margin 19 on the offset base or fla-nge 17 of the slide 15 are suiiicient to insure the movement of both slides together in the body or holder under a` push or pull imparted to either slide. f

In the adaptation of this rule to compute the time required for turning out worky on such a tool as a lathe, the upper folded margin strip 11 of the body member 10 is provided with a scale designated by F indicating the time in minutes or seconds required to finish a piece of work. On the face of the slide 15 are a `pair of upper and lower parallel scales marked E and B, the former of which indicates the length in inches, and the latter the diameter in inches of the piece of work to be turned. The calibrations of the upper sca-le E, designating the length, lie directly opposite the calibrations of the scale F carried by thebody, and indicating the time'l period.

On the face of the narrow slide 18 is a As will be seen from Fig. 5, the

scale designated by A consisting of anarrow marked and, to the right thereof, a series of calibrations designating diameters that are fractions of an inch; and beneath and parallel with the scale A is another scale designated by C, the calibrations of which indicate cutting speed in' feet per minute. The scale A. lies opposite and cooperates with the scale B carried by the slide 15.

On the lower upwardly folded margin 12 of the body is another scale D, the calibrations of which indicate the amount of feed per revolution of the lathe spindle, thesefbeing expressed in fractions'of an inch.

To illustrate'the manner of using the rule, let it be assumed that we have a piece of work twelve inches 4in diameter and seven and three-fourths inches long that we wish to turn at a cutting speed of forty-lve feet per minute, using a feed of one-sixteenth of an inch per revolution. To ascertain the time required, we first set the arrow a: on the scale A opposite the twelve inch diameter marl: on scale B, as 'shown in Fig. l. We then move both scales together, setting the cutting speed of. forty-live feet per minute on scale C opposite the feed of onesixteenth inch per revolution on scale D. Then referring to the seven and threefourths inch 'mark on scale E (length in inches), we read opposite this point on scale F the time required which, in this case, is eight and one-half minutes.

i In the great majority of cases, the diameter of the work exceeds one inch; but where the diameter of the work is less than one inch, the fraction shown on scale A (instead of the arrow m) is first set opposite the one inch mark on scale B, and the further settings are then proceeded with as above de scribed. A

From the foregoing, it will. readily be seen that, by the use of this scale, with the diameter and length of a piece of work being known, and also the feed per revolution and cutting speed per minute, by the setting of the parts of the lrule by simple sliding movements in the manner above described for the purposes of illustration, the time required to perform the operation can be ascertained at a glance on the uppermost scale F. The structural features, by which the friction between the two slides safely eX- ceeds the friction between the slides and the body, are of importance, since, after the two slides have been set to a predetermined relative position, it is essential that they be moved in unison and .without relative disturbance, since the correct registrations of the movable scale E with the stationary scale Fv are dependent upon the registrations of the movable scale C with the stationary scale D.

Obviously, so far as the structural features of the rule are concerned, the particular data carried by the body and slides are immaterial, and may be changed and adapted for` the computing of other desired 1nformation.

I claim v l. In a computing slide rule, the combination of a body, and a plurality of slides mounted on said body, said body and slides carrying cooperating scales, and said slides engaging each other under greater friction than that existing between the slides and the body, whereby said slides may first be set to a predetermined position with reference to each other, and then the slides as a unit may be moved to predetermined positions with reference to the scales carried by said body through a push or pull on one slide.

2. In a computing slide rule, the combination of a body formed with iupper and lower channel guides carrying scales, and a pair of slides carrying scales and respectively engaged with the upper and lower channel guides of said body, said slides engaging each other under greater friction than that existing between the slides and the body, whereby said slides may first be set to a predetermined position with reference to each other, and then the slides as a unit may be moved to predetermined positions with reference to the scales carried by said body through a push or pull on either slide.

3. In a computing slide rule, the combination of a body formed with upper and lower channel guides carrying scales, a slide mounted on said body and carrying a scale, said slide being frictionally engaged with the upper guide and having a base extension lying within the lower guide, and a second slide carrying a scale, said second slide resting throughout its full width upon and covering the base extension of said first slide.

4. Ina computing slide rule, the combination of a body vformed with upper and lower channel guides carrying scales, a slide mounted on said body and carrying a scale, said slide having a folded. upper margin frctionally engaged within the upper guide and having a. laterally' offset base extension lying within the lower guide, and a secondv slide carrying a scale, said second slide resting upon and covering the base extension of sald first slide and having a folded lower margin embracing the lower edge of said base extension within said lower guide.

WILLIAM L. MILLER. 

